Fork Oil Change

[matt-itude]

On my old XT it had a small screw at the bottom of the fork on each side you could drain the oil with. I notice a boss on the bottom of my kdx fork that looks like it is for just such a screw. I would love to be able to drain and refill my oil without removing the forks. has any one tried or checked into drilling this boss and installing a screw and small plastic washer/seal?

 

[glad2ride]

One might be able to do it, but there's a catch. If you drain out all the old oil through the top of the forks, then drill and tap the hole, guess what? You just put a LOT of aluminum chips into the fork, and NO they will not all rinse out. You can avoid that by completely disassembling the forks to work on JUST the outer tube, but by the time you did that, you would be in a great position to just clean it all properly. Also, once you see all the gunk that is still in the forks after just dumping the oil out of the top, you might be too surprised at the nastinessm, and decide that the drain screw method (which is even worse than dumping it out the top) is not the method for you. Drain screw are OK for damping rod style forks (like your XT had I assume), but isn't so great for all the little parts in a cartridge style fork.

 

[matt-itude]

So does everyone tear there forks down each service to clean all this out? I have been dumping the old out then pouring in some suspension oil I have laying around or atf shaking the fork around and working it up and down and repeating till the oil coming out is completely clean. How about everyone else here? I was kind of thinking about this for trying different oil weights.

 

[glad2ride]

Are you thinking that you can drill it and just rinse the aluminum bits out?

 

[19Brendan81]

My bike has such a screw in the bottom of each fork. Its a 91 with non up-side down forks.

 

[StuckinJersey]

I do the full tear down when I change the fork oil and it's not that bad or time consuming at all.
I have tried multiple different fork oil weights as well and my 96 kdx200 was effected greatly by the
different weights. I have also tried many different spring weights as well and with each change tried the 3 weights to see how it felt. On the stock well nothing felt nice, on a set of .38 kg springs from Fredette I found that a 7 weight oil work the best. 5 was not bad and 2 1/2 was terrible mostly because the rebound of the fork was far too fast since the piston in the fork was sliding a little too freely. Now I'm rocking a set of .42 kg springs from Race Tech and I found that the 5 weight is perfect, but still would like to get them working nicely with the 2 1/2. I don't know if I would attempt the drilling on the forks sounds like you might just wreck a set of forks. Good luck with it.

 

[matt-itude]

yeah. I don't want to ruin them. When I pulled the 2 shims off of the stack I broke one of the base valves that bothered me $50. So lets not even talk ruining more stuff (I know I'm a tight wad). no metal should end up inside because oil should (should being the key word) push the aluminum out. But even if I did have to tear them down now and could change oil weights that much easier I think it would be wort it. The 91s didn't have cartridge forks, but had damper rod forks, correct? but I assume the 96 has a cartridge fork and doesn't have such screw?

 

[matt-itude]

glad2ride. yes.

 

[Jaybird]

I think you could take it apart and drill a nice removal port, if you could get all the oil out from there.
If you could get all the oil out, if would make it very nice for experimentation.
Probably end up cleaner than most, actually.

 

[StuckinJersey]

Matt-itude -
Not sure about the 91 but yes the 96' (I believe introduced in 93') has a Conventional
cartridge fork. There are only 2 screws on the fork, top (air bleeder) and bottom (20-way compression clicker). I have found the conventional fork to be very easy on the oil changes though, I can usually
have both done in 20 minutes (that includes putting bike on stand, taking off tire and forks, drinking a beer, dropping rod bolt into drain pan, etc..).

 

[matt-itude]

Well the opinions have left me sitting on the fence, and I still like the idea. No one has told me anything that has scared me to death. So if I get bored, then I will post as to if this works or not.

 

[glad2ride]

I think that drilling it without having JUST the tube will allow all the aluminum chips to find their way into all the bushings and seals and not just all rinse out. IF you had JUST the outer tube and did it that way, then that may work for what it sounds like you are hoping to achieve.

Good luck with it.

 

[Dewster]

drilling this boss and installing a screw and small plastic washer/seal?

Don't do it. It's really not that difficult to pull the forks, drain the oil, refill.

Usually when I do this, I use an additional quart of fork oil to "rinse" the tubes out. There's a lot of gunk that builds up in there and I don't see how it would all come out through a 1/4" hole. I would be kinda like changing the oil in your car without changing the filter.

 

[Robcolo]

That boss was made for a drain hole--my old '88 Kx 250 had identical forks to the current KDX ones and that boss was drilled & tapped OEM. First time I disassembled the DX forks, I drilled & tapped it [8-32 I think] when they're apart it's quite easy to drill, tap & rinse out the chips. It does make routine oil changes a breeze. I drain, then rinse several times with kerosene to "get the sludge out"
Someone mentioned too fast rebound with heavier springs --When you remove 2 of the base valve shims you can add one or both of these to the rebound stack to "stiffen up" there.

 

[glad2ride]

There MAY be a reason why they haven't had a drain screw in a looooong time. :-)

You will NEVER, EVER, get all the sludge out with rinsing. If you are happy with some/most, then go for it, but just don't think you are getting it all out, even if you THINK you got it all out.

Please don't use kerosene to rinse the forks. Thank you from a member of the Society for Prevention of Cruelty to O-rings

 

[Jeff Sexton]

Just my two cents worth...

The KDX seems to go through guide bushings unusually fast compared to other bikes I've owned. If the teflon (or whatever it is) peels off the guide bushings and you're not disassembling the fork to properly clean the forks and change the oil, then you won't know you have a problem until you start to notice the scratches in your fork tubes. This assumes that you pull down the fork boots occasionally to check for this. It seems to me that a set of fork tubes would be way more expensive in the long run than the extra hour or so it would take to do it right.

Again, just my two cents worth.

 

[COMBEN]

just a thought...

If you were say, experimenting with different oil weights or something and wanted a quick, easy and clean way of draining the fork tubes, well I have seen a great tool for the job...
The mechanic I use for our car stock has an 'oil sucker' he uses for oil changes on our cars...he just pumps the tool up, places the tool's 1/4" pipe down the dipstick hole and 'hey presto' the tool sucks out the old oil. He can sometimes actually get more oil out this way as the pipe gets right down into the sump and some sump oil plugs are slightly higher than the oil level...BMW's come to mind!

like I said just a thought ;)

Richard

 

[Kwakasaki]

Exscuse me Jersey but that should be 22 minutes. You didnt include the second beer! :nener:

 

[matt-itude]

Ok the general consensus seems to be (a) it wont hurt anything if I get all the metal out when I do it. (b) that when using the drains that I would never get all the sludge etc out of the forks (c) even for just trying different weight oils most would prefer to just pull the forks off rather than just drink beer while the forks just drain out on the bike stand (I dont drink so I would have to find something else to do). I still havent found anyone who has tried this. Its ok because I am different or like to be anyways.